The present embodiments relate to devices and methods for detecting a position of at least one magnetic resonance tomography (MRT) local coil in an MRT system.
Magnetic resonance devices (e.g., MRTs) for examining objects or patients using magnetic resonance tomography are, for example, known from U.S. Pat. No. 7,696,754B2, DE102009021026 A1, DE102009018282 A1, DE102009004448 A1, and CN101887108A.
In nuclear spin tomography, local coils are positioned on a table (PTAB).
To improve the workflow, the MRT system may automatically move a region of interest (RoI) of a patient to be examined using imaging into the center of a magnetic homogeneity volume (e.g., field of view (FoV)), and start the imaging MRT examination of the RoI there. For this purpose, where the ROI is located on the table should be known.
In the case of certain local coils, the RoI is largely defined by the local coil (e.g., in the case of a chest coil, the chest region is examined). The local coil may therefore be used as information for the RoI. The system knows, for example, via local coil identification, which local coil is connected but not necessarily where precisely this local coil was positioned on the table.
Known methods, in which a first movement of the table that moves the patient into the measuring volume FoV after positioning on the table, are based on mechanical coding. For example, for the chest coil, holes/slits are indicated in the patient table PTAB, and the local coil is mechanically shaped such that the local coil is to be positioned in the hole in the table using a small “lug.” Using detection (e.g., identification) of the local coil, the system then adopts a fixed position of the local coil on the table, which is indicated in a software file (e.g., as a distance from an end of the table). The information with regard to PTAB movement (e.g., where the PTAB should move to) is therefore obtained from a combination of local coil identification, mechanical coding and software information.
This implementation may have the following disadvantages. The local coils positioned on the PTAB may, for example, be relatively large in the case of a chest coil and are defined by small mechanical retention devices in the z position. This is disadvantageous because it is difficult to put the relatively large part into a small hole. It is easy for the local coil to be incorrectly positioned and for the mechanical coding not to work correctly. The system then moves the patient to a suboptimal position. For some applications, positioning at only one mechanically fixed predetermined point may be disadvantageous because with the different body sizes of patients, the knees, for example, may come to rest at somewhat different z positions. For example, for very large women, a more flexible positioning of the chest coil in the z direction may result in greater comfort for the patient.
In general, the concept of mechanical coding may have the disadvantage that a patient is to be positioned on the table relative to a predefined position of the local coil, and the positioning of the patient from the point of view of the workflow or of patient comfort is less possible. This applies, for example, in the case of a knee coil where it is clearly apparent where precisely the knee is positioned after the patient is lying on the table. For this application too, being able to position the coil more independently of mechanical markers with simultaneous detection of the coil position is desirable.